About three-fourths of middle-aged and older women are sexually active and two-thirds of them are at least somewhat satisfied, according to a new study. Black women are more satisfied with their sex lives than their white counterparts.

Dr. Ilana B. Addis of the University of Arizona in Tucson and colleagues also found in their survey of just over 2,000 women aged 40 to 69 that better mental health was associated with more sexual satisfaction, while heavier women were less likely to be sexually satisfied.

There has been little research on the sex lives of middle aged and older women, in particular on sexual dysfunction among women in this age group, Addis and her colleagues write in the April issue of Obstetrics & Gynecology.

To investigate, they analyzed results from 2,109 women participating in a study of incontinence, all of whom were long-term members of California's Kaiser Permanente health plan. The women had completed questionnaires on how frequently they had sex, their satisfaction with their sex lives, and any sexual problems.

Seventy-one percent of the women reported having sex in the past year, while 37% had sex monthly or less often and 33% had sex weekly or more frequently. One-third of sexually active women reported having some type of sexual dysfunction, including lack of interest in sex, inability to relax and enjoy sex, or difficulty in becoming aroused or having an orgasm.

Twenty-four percent of the sexually active women said sexual dysfunction was "somewhat of a problem" or "very much of a problem."

Richer or more highly educated women had more sex, the researchers found, while moderate alcohol consumption, lower body mass index and better health also were tied to more frequent sexual activity. Younger women and those in a significant relationship were also more likely to have sex more frequently.

African-American women were 32% less likely than whites to report being dissatisfied with their sex lives. The researchers also identified a link between better mental health and more sexual satisfaction, and higher body mass index and less satisfaction.